1. Field of the Invention
The invention relates to the vapor phase catalytic oxidation of alpha,beta-unsaturated monoolefins to the corresponding alpha,beta-unsaturated carboxylic acids and alpha,beta-unsaturated aldehydes.
2. Description of the Prior Art
The use of oxidation catalysts containing molybdenum and bismuth, alone, or with other selected elements, for the gas phase oxidation of alpha,beta-unsaturated monoolefins such as propylene to the corresponding alpha,beta-unsaturated acid and/or aldehyde, such as acrylic acid and acrolein, has been known.
In these reactions a gaseous reaction mixture which usually contains the olefin, molecular oxygen and water, as steam, is brought into contact with the catalyst, by continuously passing a stream of the reaction mixture through a bed of the catalyst. Such known catalyst systems would include those disclosed in the following U.S. Pat. Nos.: 3,171,859; 3,387,038; 3,445,521; 3,522,299; 3,636,066; 3,642,930; 3,679,603 and 3,691,096.
For commercial purposes this group of catalysts usually comprise the elements Mo, Bi, Fe and Ni and/or Co. In order to improve on the efficiency and/or productivity of such catalyst compositions, and/or the selectivity of the products made with such catalyst compositions it has been desirable, as disclosed in some of the above noted patents, to add additional elements to the catalyst composition.
A review of the prior art and the present applicant's work, as illustrated in the examples disclosed below, indicates that the selection of additional elements to be used in combination with the Mo-Bi-Fe-Ni and/or Co based catalyst compositions, to provide the above mentioned improvements, is not an obvious procedure.
The terms % conversion, productivity and % selectivity or efficiency which are employed herein with respect to the present invention are defined as follows (based on the composition of the gas exiting from the catalyst bed):
I % conversion = (A - B/A) .times. 100
where
A = total mol equivalents of olefin fed to the catalyst bed
B = mol equivalents of unconverted olefin in gas exiting from the catalyst bed
II % Efficiency = (C/A - B) .times. 100
where
A and B are as defined above and
C = the mol equivalents of olefin which are present in the alpha,beta-unsaturated carboxylic acid and alpha,beta-unsaturated aldehyde which are produced.
III productivity = pounds of alpha,beta-unsaturated aldehyde and/or alpha,beta-unsaturated carboxylic acid produced per cubic foot of catalyst (in the catalyst bed) per hour of reaction time.